A color diffusion transfer type photograph material (so-called instant photograph), a heat developing color diffusion transfer process, a method in which a photosensitive microcapsules are used and the like are known as the method in which an image forming dye is formed or released making use of a silver halide and an image is formed by transferring the dye.
Since the light resistance of images obtained by these methods is generally inferior to that of the images of usual photograph process, various methods have been proposed with the aim of improving the light resistance.
As one of these methods, an ultraviolet absorber is used. In such a method, the light resistance is improved by reducing the quantity of light to be irradiated upon a color image by the use of an ultraviolet absorber. This method can inhibit fading caused by ultraviolet light but has no effect on fading caused by visible light. It also has a disadvantage in that images fade and weather by the ultraviolet absorber.
In a secondary matter, it requires a relatively large amount of the ultraviolet absorber in order to improve the light resistance sufficiently. The use of a large amount of the ultraviolet absorber entails increment of coating thickness, thus resulting in various problems such as prolonged period of transfer time, reduction of resolution, aggravation of useful capacity and the like, as well as reduction of film strength and precipitation of the ultraviolet absorber.
In addition, this method cannot provide sufficient light resistance due to its fundamental problems such as reduction of fluorescent brightness, aggravation of brightness and the like.
Also, studies have been conducted on various fading inhibitors which are used in so-called conventional photograph system. However, even a fading inhibitor which is useful in the conventional photograph system cannot exert sufficient effects in the photograph method of the present invention in which an image is formed by transferring a dye.
JP-B-49-20974 (the term "JP-B" as used herein means an "examined Japanese patent publication") and JP-A-62-144162 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") disclose the use of specified piperidine derivatives as fading inhibitors in image receiving materials (image receiving layer and the like) which are used in the color diffusion transfer process.
However, the light fading-inhibiting effect of the piperidine derivatives disclosed therein on transfer dye images is not sufficient so that further improvement is required.
In addition, JP-A-4-125559 disclose the addition of a specified piperidine derivative to an image receiving material (dye fixing element) which is used in the color diffusion transfer process, in order to inhibit changes in the density of white ground portions. However, the lipophilic piperidine derivative illustratively disclosed therein has insufficient light fading-inhibiting effect on transfer dye images.